HEADS IN PROFILE 377 
ance to know what kind of person this Bury St Edmunds 
fragment belonged to, for it is the only human fragment 
so far found in England belonging to the very remote 
mid-Pleistocene Acheulean age. 
When I began my investigations one point became 
very evident ; the method we employ in measuring and 
recording modern skulls and heads was useless. For 
that purpose we give the head or skull a definite pose ; 
we place it so that the ear-hole and the lower margin 
of the orbit are on a level, on the same plane — the 
Frankfurt plane. In ancient skulls the lower part of the 
orbit is nearly always broken away ; often the temporal 
bone, with the necessary ear-passage, is missing. As a 
rule little more than the vault of fossil skulls is found ; 
therefore in the vault we must find the base line from 
which we are to reconstruct the whole skull. Now on 
the vault there are two very definite points which, at 
first sight, would seem to serve our purpose. At the 
front end, on the lower brink of the forehead, just over 
the root of the nose, is the projection or point known as 
the glabella (fig. 136). At the hinder end, just where 
the vault slopes down to join the neck, is a well-marked 
projection — the inion or external occipital protuberance 
(fig. 136, O). A line drawn from the glabella in front to 
the inion behind would seem to provide us with the kind 
of base line we need for the reconstruction of the missing 
parts of the skull. I could not accept these points 
because I knew them to be — at least in certain skulls — 
movable and variable in position as regards the brain, 
and the points needed for a base line must be fixed, at 
least as regards their relationship to the brain. In the 
young anthropoid ape both glabella and inion are low 
down near the base of the skull. The vault of the skull 
rises high above a base line joining those two points. 
As the young ape grows the muscles of mastication 
increase in size, the neck increases in thickness, with the 
result that the glabella and inion ascend towards the 
vault of the skull (fig. 136). Hence in the adult the 
vault of the skull appears to be lower than in the young. 
